CONSTRAINTS ON THE EVOLUTION OF REMNANT PROTOSTELLAR DUST DEBRIS AROUND HR-4796

We have obtained optical spectra and J, H, K, and 20 mum photometry of the components of HR 4796, whose component A (m(v) = 5.8 mag) is a main-sequence A-type star with a large fractional infrared excess (L(IR)/L* = 5 x 10(-3)), produced by circumstellar dust. Component B (m(v) = 12.7 mag), located 7''7 away from component A, is an early M-type star. During the past 60 years, it appears that HR 4796A and B have had nearly the same proper motion; they are likely to be a physical pair. The luminosity of HR 4796B is about 0.15 L., and with T(eff) approximately 3300 K, it lies well above the main sequence, and thus has an estimated age of about 3 x 10(6) years. Since HR 4796A is young, we suggest that the current circumstellar dust is a remnant of the protostellar nebula, consistent with our estimate for the lifetime due to the Poynting-Robertson effect of large (a > 10 mum) dust grains around HR 4796A. If this is the case, then HR 4796A may be in a common phase of the early evolution of many main-sequence A stars.